Owing to the increasing energy demands and the environmental constraints,the need for bio-based materials has been on the rise due to their variety of favorable properties like biocompatibility,cost-effectiveness,larg...Owing to the increasing energy demands and the environmental constraints,the need for bio-based materials has been on the rise due to their variety of favorable properties like biocompatibility,cost-effectiveness,large specific surface area,high porosity,and non-toxicity.Thermal stability and mechanical strength of aerogels are highly dependent on their micro-porous structures.A three-dimensional structure based on cellulose nanofiber/chitosan(CNF/CS)aerogels was built using two different freezing methodologies,namely random freezing,and unidirectional freezing techniques,by changing mold shapes.The unidirectional aerogels ultimately resulted in high-temperature stability and mechanical strength.The results show that the unidirectional CNF/CS(u-CNF/CS)aerogels contain controlled micro porous orientation relative to random-CNF/CS(r-CNF/CS)aerogels with the disordered porous distribution.The high-temperature stability with an increase of glass transition temperature T_(g) from 275℃(CNF)to 283℃(CNF/CS),the ultra-low thermal conductivity of 0.030 W/(m·K),and mechanical robustness of u-CNF/CS aerogels make them quite favorable for practical applications.展开更多
基金National Key Research and Development Program of China(No.2018YFC2000900)。
文摘Owing to the increasing energy demands and the environmental constraints,the need for bio-based materials has been on the rise due to their variety of favorable properties like biocompatibility,cost-effectiveness,large specific surface area,high porosity,and non-toxicity.Thermal stability and mechanical strength of aerogels are highly dependent on their micro-porous structures.A three-dimensional structure based on cellulose nanofiber/chitosan(CNF/CS)aerogels was built using two different freezing methodologies,namely random freezing,and unidirectional freezing techniques,by changing mold shapes.The unidirectional aerogels ultimately resulted in high-temperature stability and mechanical strength.The results show that the unidirectional CNF/CS(u-CNF/CS)aerogels contain controlled micro porous orientation relative to random-CNF/CS(r-CNF/CS)aerogels with the disordered porous distribution.The high-temperature stability with an increase of glass transition temperature T_(g) from 275℃(CNF)to 283℃(CNF/CS),the ultra-low thermal conductivity of 0.030 W/(m·K),and mechanical robustness of u-CNF/CS aerogels make them quite favorable for practical applications.
